POSIX is Dead!Long Live... errr... What Exactly?
July 10, 2017 POSUX talk (HotStorage’17 WACI) 1
Erez Zadok, Dean Hildebrand,
Geoff Kuenning, and
Keith Smith
Stony Brook University
IBM Research -Almaden
Harvey Mudd College
NetApp
The Problem with POSIX (1)
• POSIX is ~30 years oldHuge advancements in computingDeeper, more complex storage stack
• Inefficient use of resourcesDesigned for serial/sync data accessToday: faster, more complex, heterogeneous hardware§ Parallelism, clouds
July 10, 2017 2POSUX talk (HotStorage’17 WACI)
The Problem with POSIX (2)• Security: Huh? What’s
that? E.g., TOCTTOU bugs
• Assumes files and namespaces
Hard to manage many files
• Byte-level accessOverkill for Objects?
July 10, 2017 POSUX talk (HotStorage’17 WACI) 3
Worst.API.Ever.
How Do You Solve a Problem Like…• Abolish POSIX!• New API
Works with files, objects, extents, etc.
• Minimal set of native callsE.g., really need symlinks/hardlinks?!
• Security from day one• Efficiency
Asynchrony, compounding, API v2
July 10, 2017 4POSUX talk (HotStorage’17 WACI)
Increasing Efficiency (1)
• Compounding (bulk updates)Pack multiple request in one messageSaves latency, fewer context switchesMultiple failure semantics§ First-fail§ Continue-on-fail§ Transactional
Simple if-then-else and looping syntax
July 10, 2017 5POSUX talk (HotStorage’17 WACI)
[FAST’17, HOTOS’03]
Increasing Efficiency (2)
• Asynchrony everywhereEncourages more parallel “thinking”CPU speeds vs. #cores
• API changesGive a “handle” to operate on a collection of files/objects§ Locking, leases/delegations, recalls
Avoid passing same info repeatedly§ E.g., /bin/cp passes same pathname
Improves security and reliability
July 10, 2017 6POSUX talk (HotStorage’17 WACI)
[FAST’17, HOTOS’03]
Implementation
• Low-level vs. high-level compounding API
Low-level: allow compounding anythingHigh-level: useful APIs to developers
• Offer begin/end APIsMark code segments for compoundingNeeds compiler/language support, code-analysis
July 10, 2017 7POSUX talk (HotStorage’17 WACI)
Transitioning
• Implement most common requests firste.g., read/write-whole-file, copy-file, rename-multiple-objects, rm-*
• Offer transactional semantics early onRequires support all the way through the storage/OS/network stack
July 10, 2017 8POSUX talk (HotStorage’17 WACI)
Why Migrate?Mainly for performance,
then security.
POSIX is Dead!Long Live... errr... What Exactly?
July 10, 2017 POSUX talk (HotStorage’17 WACI) 9
Erez Zadok, Dean Hildebrand,
Geoff Kuenning, and
Keith Smith
Stony Brook University
IBM Research -Almaden
Harvey Mudd College
NetApp
Q&A
